Archived
add Linux admin user setup as part of node hardening
New script setup-linux-admin-user.sh creates the Linux system user, installs an SSH authorized key, and adds the user to the sudo group. Integrated into bootstrap.sh before harden-ssh.sh so key-based access is in place before password authentication is disabled. bootstrap.sh now accepts ADMIN_USER and ADMIN_SSH_KEY env vars to run user setup and setup-admin-sudo.sh automatically at the right point. audit.sh checks that at least one non-root user has an authorized key. docs/04-security-hardening.md updated with the new steps and ordering. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Claude Sonnet 4.6
@@ -16,24 +16,31 @@ Then run `scripts/audit.sh` to verify. Order matters (matches
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| # | Item | Script | Manual step required? |
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|---|------|--------|------------------------|
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| 1 | Remove enterprise repos, switch to no-subscription | `switch-to-no-subscription-repo.sh` | no |
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| 2 | SSH: key-only root login + fail2ban | `harden-ssh.sh` | no (requires an `authorized_keys` already in place — script warns if missing) |
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| 3 | Unattended security upgrades, no auto-reboot | `setup-unattended-upgrades.sh` | no |
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| 4 | PVE firewall, default-deny, mgmt-only SSH/8006 | `deploy-firewall.sh` | needs `MGMT_CIDR` set |
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| 5 | Disable subscription nag (cosmetic) | `disable-subscription-nag.sh` | no |
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| 6 | Named PVE admin user, Administrator role | `create-admin-user.sh <username>` | yes — pick the username, change the generated password on first login |
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| 7 | 2FA/TOTP on that user and `root@pam` | — | yes — web UI only: Datacenter → Permissions → Two Factor, or user menu → TFA |
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| 8 | Verify everything above | `audit.sh` | no |
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| 2 | Linux admin user with SSH key + sudo access | `setup-linux-admin-user.sh <user> <pubkey>` | yes — choose a username and provide your SSH public key. Run this **before** SSH hardening or pass `ADMIN_USER`/`ADMIN_SSH_KEY` to `bootstrap.sh` so it runs automatically at the right point |
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| 3 | Passwordless sudo for pvesh/qm/pct | `setup-admin-sudo.sh <username>` | yes — same username as step 2 |
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| 4 | SSH: key-only root login + fail2ban | `harden-ssh.sh` | no — step 2 ensures authorized_keys are in place first |
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| 5 | Unattended security upgrades, no auto-reboot | `setup-unattended-upgrades.sh` | no |
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| 6 | PVE firewall, default-deny, mgmt-only SSH/8006 | `deploy-firewall.sh` | needs `MGMT_CIDR` set |
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| 7 | Disable subscription nag (cosmetic) | `disable-subscription-nag.sh` | no |
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| 8 | Named PVE admin user, Administrator role | `create-admin-user.sh <username>` | yes — pick the username, change the generated password on first login |
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| 9 | 2FA/TOTP on that user and `root@pam` | — | yes — web UI only: Datacenter → Permissions → Two Factor, or user menu → TFA |
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| 10 | Verify everything above | `audit.sh` | no |
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## Linux/SSH layer
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- A named Linux system user (created by `setup-linux-admin-user.sh`) with an
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SSH authorized key and `sudo` group membership is the primary SSH login
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account. Root SSH is locked to key-only after `harden-ssh.sh` runs; the
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Linux admin user is how you get shell access day-to-day without using root.
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- `setup-admin-sudo.sh` adds a narrower, password-free sudoers rule for the
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Proxmox management tools (`pvesh`, `qm`, `pct`) specifically — needed for
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non-interactive automation scripts that SSH in and run these tools without a
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TTY.
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- `PermitRootLogin prohibit-password` in `sshd_config` — root can only
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log in via SSH key, never password. Kills most brute-force attempts.
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- fail2ban jail for SSH on top of that.
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- Restrict SSH to the management VLAN/trusted IPs via the Proxmox
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firewall (see `03-networking.md`) rather than exposing broadly.
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- A separate Linux sudo user isn't strictly required for day-to-day PVE
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admin (the PVE permission system below governs that), but worth adding
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if multiple people SSH into the box directly, for accountability.
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## PVE/web layer (the one that actually matters day-to-day)
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@@ -69,6 +69,22 @@ if [ -f /var/run/reboot-required ]; then
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audit_warn "a reboot is pending (/var/run/reboot-required) - schedule one"
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fi
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# --- Linux admin user with SSH key (for non-root SSH login) ---
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LINUX_ADMIN_OK=0
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for auth_file in /home/*/.ssh/authorized_keys; do
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[ -f "$auth_file" ] || continue
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# Must have at least one non-comment, non-empty key line.
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if grep -qE '^(ssh-rsa|ssh-ed25519|ecdsa-sha2-nistp[0-9]+) ' "$auth_file" 2>/dev/null; then
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LINUX_ADMIN_OK=1
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break
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fi
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done
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if [ "$LINUX_ADMIN_OK" -eq 1 ]; then
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audit_pass "a non-root Linux user has an SSH authorized key"
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else
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audit_fail "no non-root Linux user has an authorized SSH key (run setup-linux-admin-user.sh)"
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fi
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# --- named admin user (not just root@pam) ---
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if pveum user list --output-format json 2>/dev/null | grep -q '"userid":"[^"]*@pve"'; then
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audit_pass "a named @pve admin user exists (root@pam is not the only account)"
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+36
-15
@@ -2,11 +2,15 @@
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# Stage 1 base config + hardening, end to end, for a single fresh PVE host.
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# Runs the individual scripts in order. Idempotent - safe to re-run.
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#
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# Does NOT create the named admin user (needs a username decision) - run
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# create-admin-user.sh separately afterwards. Run audit.sh at the end to
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# verify.
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# If ADMIN_USER and ADMIN_SSH_KEY are set, a Linux system user is created
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# with SSH key access and sudo before SSH hardening runs - so key-based
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# login is in place before password auth is disabled. If they are not set,
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# a reminder is printed at the end to run setup-linux-admin-user.sh manually
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# (but do this BEFORE disconnecting, since password auth will be disabled).
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#
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# Usage: MGMT_CIDR=192.168.2.0/24 ./bootstrap.sh
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# Usage:
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# MGMT_CIDR=192.168.2.0/24 ./bootstrap.sh
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# MGMT_CIDR=192.168.2.0/24 ADMIN_USER=wayne ADMIN_SSH_KEY="ssh-ed25519 ..." ./bootstrap.sh
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set -euo pipefail
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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@@ -19,28 +23,45 @@ if [ -z "${MGMT_CIDR:-}" ]; then
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exit 1
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fi
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echo "=== 1/5: remove enterprise repos, switch to no-subscription ==="
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STEP=0
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next_step() { STEP=$((STEP + 1)); echo; echo "=== ${STEP}: $* ==="; }
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next_step "remove enterprise repos, switch to no-subscription"
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"${SCRIPT_DIR}/switch-to-no-subscription-repo.sh"
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echo
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echo "=== 2/5: SSH hardening (key-only root login + fail2ban) ==="
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# Create the Linux admin user before SSH hardening so that authorized_keys
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# is in place before password auth is disabled.
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if [ -n "${ADMIN_USER:-}" ] && [ -n "${ADMIN_SSH_KEY:-}" ]; then
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next_step "Linux admin user '${ADMIN_USER}' + SSH key + sudo group"
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"${SCRIPT_DIR}/setup-linux-admin-user.sh" "$ADMIN_USER" "$ADMIN_SSH_KEY"
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next_step "passwordless sudo for pvesh/qm/pct (${ADMIN_USER})"
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"${SCRIPT_DIR}/setup-admin-sudo.sh" "$ADMIN_USER"
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else
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echo
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echo "WARNING: ADMIN_USER / ADMIN_SSH_KEY not set -- skipping Linux user setup."
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echo " Run setup-linux-admin-user.sh and setup-admin-sudo.sh BEFORE disconnecting"
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echo " from this session, since the next step disables password authentication."
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fi
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next_step "SSH hardening (key-only root login + fail2ban)"
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"${SCRIPT_DIR}/harden-ssh.sh"
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echo
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echo "=== 3/5: unattended security upgrades ==="
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next_step "unattended security upgrades"
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"${SCRIPT_DIR}/setup-unattended-upgrades.sh"
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echo
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echo "=== 4/5: PVE firewall (mgmt-only SSH/8006) ==="
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next_step "PVE firewall (mgmt-only SSH/8006)"
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MGMT_CIDR="$MGMT_CIDR" "${SCRIPT_DIR}/deploy-firewall.sh"
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echo
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echo "=== 5/5: disable subscription nag (cosmetic) ==="
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next_step "disable subscription nag (cosmetic)"
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"${SCRIPT_DIR}/disable-subscription-nag.sh"
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echo
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echo "=== Base hardening applied. Remaining manual/deliberate steps: ==="
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echo " - ${SCRIPT_DIR}/create-admin-user.sh <username>"
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echo " - ${SCRIPT_DIR}/setup-admin-sudo.sh <username> (passwordless sudo for pvesh/qm/pct)"
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if [ -z "${ADMIN_USER:-}" ]; then
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echo " - ${SCRIPT_DIR}/setup-linux-admin-user.sh <username> <ssh-pubkey>"
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echo " - ${SCRIPT_DIR}/setup-admin-sudo.sh <username> (NOPASSWD for pvesh/qm/pct)"
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fi
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echo " - ${SCRIPT_DIR}/create-admin-user.sh <username> (PVE web UI account)"
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echo " - Enable 2FA/TOTP for that user and root@pam via the web UI"
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echo " - ${SCRIPT_DIR}/audit.sh (verify everything above)"
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Executable
+82
@@ -0,0 +1,82 @@
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#!/bin/bash
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# Create a Linux system user for SSH access and sudo, and install their
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# authorized SSH public key. Run this before harden-ssh.sh so that
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# key-based access is in place before password authentication is disabled.
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#
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# Idempotent - safe to re-run. Run as root on the PVE host.
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#
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# Usage:
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# ./setup-linux-admin-user.sh <username> <ssh-public-key>
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# ./setup-linux-admin-user.sh <username> --key-file <path-to-.pub>
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set -euo pipefail
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SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
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# shellcheck source=lib/common.sh
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source "${SCRIPT_DIR}/lib/common.sh"
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require_root
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USERNAME="${1:-}"
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if [ -z "$USERNAME" ]; then
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echo "Usage: $0 <username> <ssh-public-key>" >&2
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echo " $0 <username> --key-file <path-to-.pub>" >&2
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exit 1
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fi
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shift
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SSH_KEY=""
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if [ "${1:-}" = "--key-file" ]; then
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KEY_FILE="${2:-}"
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[ -z "$KEY_FILE" ] && { echo "ERROR: --key-file requires a path." >&2; exit 1; }
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[ -f "$KEY_FILE" ] || { echo "ERROR: key file not found: $KEY_FILE" >&2; exit 1; }
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SSH_KEY="$(cat "$KEY_FILE")"
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else
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SSH_KEY="${1:-}"
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fi
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if [ -z "$SSH_KEY" ]; then
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echo "ERROR: an SSH public key is required (key string or --key-file <path>)." >&2
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exit 1
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fi
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if ! echo "$SSH_KEY" | grep -qE '^(ssh-rsa|ssh-ed25519|ecdsa-sha2-nistp[0-9]+) [A-Za-z0-9+/=]'; then
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echo "ERROR: argument doesn't look like a valid SSH public key." >&2
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exit 1
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fi
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# --- create Linux user if missing ---
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if id "$USERNAME" >/dev/null 2>&1; then
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echo "User '${USERNAME}' already exists - skipping useradd."
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else
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useradd --create-home --shell /bin/bash "$USERNAME"
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echo "Created Linux user '${USERNAME}'."
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fi
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# --- sudo group membership ---
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if id -nG "$USERNAME" | grep -qw sudo; then
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echo "User '${USERNAME}' is already in the sudo group."
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else
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usermod --append --groups sudo "$USERNAME"
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echo "Added '${USERNAME}' to the sudo group."
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fi
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# --- install authorized SSH key ---
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HOME_DIR="$(getent passwd "$USERNAME" | cut -d: -f6)"
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SSH_DIR="${HOME_DIR}/.ssh"
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AUTH_FILE="${SSH_DIR}/authorized_keys"
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mkdir -p "$SSH_DIR"
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chmod 700 "$SSH_DIR"
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touch "$AUTH_FILE"
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chmod 600 "$AUTH_FILE"
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chown -R "${USERNAME}:${USERNAME}" "$SSH_DIR"
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if grep -qF "$SSH_KEY" "$AUTH_FILE" 2>/dev/null; then
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echo "SSH key is already present in ${AUTH_FILE}."
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else
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echo "$SSH_KEY" >> "$AUTH_FILE"
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echo "Installed SSH key in ${AUTH_FILE}."
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fi
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echo
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echo "Linux user '${USERNAME}' is ready for SSH key-based login with sudo access."
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echo "Next: run setup-admin-sudo.sh ${USERNAME} to grant NOPASSWD for pvesh/qm/pct."
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